1. Field of the Invention
The present invention relates to a laser irradiation apparatus which is capable of selecting a laser light having a wavelength among a plurality of laser lights having different wavelengths according to the purpose of the irradiation and irradiating an object to be irradiated with the laser light having the wavelength and, in particular, relates to a downsized laser irradiation apparatus capable of extracting from a mixed laser light of a plurality of laser lights having different wavelengths a laser light having the shortest wavelength with high wavelength purity, and a bright point correction method for a liquid crystal display panel using such an apparatus.
2. Description of Related Art
Conventionally, this sort of laser irradiation apparatus is provided with a first laser generator which generates a first laser light having a short wavelength and a second laser generator which generates a second laser light having a longer wavelength than the first laser light. The laser irradiation apparatus is configured to irradiate a liquid crystal cell of a bright defect of a liquid crystal display panel with the first laser light, to make a color filter of the liquid crystal cell peel from a substrate to form a gap between them, and thereafter, irradiate the liquid crystal cell with the second laser light to change the physical properties of the color filter of the liquid crystal cell so that its light transmittance drops (for example, refer to Japanese Laid-open (Kokai) Patent Application Publication No. 2008-165164 A).
However, since such a conventional laser irradiation apparatus has two laser generators for generating two laser lights having different wavelengths, and is configured to switch ON and OFF states of these generators to extract a laser light having a specific wavelength, it is difficult to downsize the apparatus.
On the other hand, it can be considered to generate harmonic waves from basic waves of a single laser generator to obtain a plurality of laser lights having different wavelengths, and thereafter, wavelength-separates the plurality of laser lights having different wavelengths, for example, by using a dichroic mirror, and make the plurality of laser lights having different wavelengths pass through respective optical paths, and open and close each optical path to extract a laser light having specific a wavelength. However, in this method, since the plurality of optical paths is provided so as to spread in the lateral direction, it is not easy to downsize the apparatus.
Further, it is also possible to extract a laser light having a specific wavelength by using a filter from mixed laser lights having different wavelengths which propagate the same optical path; however, due to characteristics of a filter, it is difficult to extract with high wavelength purity, for example, a laser light of 266 nm separately from a laser light having a close wavelength of 355 nm. Accordingly, when, for example, a laser light of 266 nm is used to peel a color filter of a liquid crystal cell of a bright defect in order to correct the bright defect of a liquid crystal display panel, there is a risk that a residual laser light of 355 nm that is not removed by the filter causes a thermal influence on a surrounding area of the liquid crystal cell.